1. Field of the Invention
The present invention relates to the removal of residual peroxides from vegetable matter that has been bleached with hydrogen peroxide and then dried.
2. Description of the Prior Art
Vegetable matter bleached with H.sub.2 O.sub.2 and then dried is obtained from pulps, cereals, seeds, flours, brans, fruits, including citrus fruits, or vegetables, depending on the particular case, after, e.g., the extraction or isolation of the normally reclaimable constituents therefrom, such as sugar, fruit juice, pectin, flour, starch or oil, etc.
Exemplary such original materials include sugar beets, wheat, corn oats, barley, apples, peaches, pears, apricots, peas and oil-containing plants such as the sunflower, soya, the groundnut and the coconut.
Bleaching of these materials can be carried out with the aid of hydrogen peroxide, for example by the process described in U.S. Pat. No. 4,241,093.
Matter bleached in this manner is reduced to the dry state, namely, devoid of any liquid content distinct from that in the solid matter. Its content by weight of water can then be approximately 20%, but in many cases, such as, for example, bleached flours or sugar beet pulp, such content does not exceed approximately 10% to 11%.
The vegetable matter thus bleached with hydrogen peroxide and then dried shall hereinafter be referred to as "vegetable fiber".
Such vegetable fiber is useful, in particular, for the production of foodstuffs and edible comestibles destined for human consumption, notably dietetic products.
The vegetable fibers have a residual peroxide content which is generally too high to be compatible with various requirements for human foods.
As utilized herein, by the term "peroxides" are intended hydrogen peroxide and the peroxidized precursors thereof.
The peroxide content of the ultimate foodstuffs must be extremely low, even nil if possible.
Any treatments of such foodstuffs before they are marketed to the consumer must be adapted to the constitution of the particular edible foodstuff in each case. Therefore, they are extremely diversified in their nature and specific treatments are required for each individual material making an overall processing operation very costly.
For example, the hydrogen peroxide present in various foodstuffs, in most cases, and furthermore those of animal origin, is removed in one instance by means of red algae or extracts thereof (see published Japanese Kokai 72/04,982), in another instance by means of a mixture of a compound of iron and of sugars (see published Japanese Kokai 77/07,388, and in yet another instance by means of catalase according to IIDA Toshiyuki, Fukumi Toru, Hokusuishi Geppo, 39(9), 242-255 (1982).
With regard to the removal of peroxides remaining in a vegetable matter after its bleaching with hydrogen peroxide, published Japanese Kokai 77/125,657 describes a process which, akin to those referred to above, requires the use of additives to the vegetable fiber, in this case water and the unbleached original vegetable matter. Such a process presents the dual disadvantage of dilution with water and a reversal of processing efficiency in respect of whiteness of the very matter, which has just been bleached and dehydrated.